<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        
    </style>
</head>
<body>
    
</body>
<script>
    var str = "azAZ09";

    console.log( str.charCodeAt(0) );
    console.log( str.charCodeAt(1) );

    console.log( str.charCodeAt(2) );
    console.log( str.charCodeAt(3) );

    console.log( str.charCodeAt(4) );
    console.log( str.charCodeAt(5) );

    console.log( String.fromCharCode(91) );
    console.log( String.fromCharCode(92) );
    console.log( String.fromCharCode(93) );
    console.log( String.fromCharCode(94) );
    console.log( String.fromCharCode(95) );

    // =========

    console.log( "中".charCodeAt() );
    console.log( String.fromCharCode(20014) );
    console.log( String.fromCharCode(20012) );

    // =========

    console.log(  String.fromCharCode(20013)  );
    console.log(  String.fromCharCode( "0x4E2D" )  );

    // =========

    console.log( 20013 );
    console.log( "0x4E2D" );
    
    console.log( "\u4E2D" );


</script>
</html>